基于共面电容传感器的便携式预应力管道灌浆质量检测系统设计

预应力管道灌浆质量事关桥梁安危,因此,提出了一种基于共面电容传感器的预应力管道灌浆质量检测系统,能够检测预应力管道内灌浆分层状况.利用前期推导的平行共面电容传感器半解析方程确定了优化参数的共面电容传感器.基于相邻电容测量原理设计了数据采集单元、数据转换单元.为完善系统,设计了相应的系统控制单元与数据显示单元.依据近似理论,设计了系统验证试验,通过改变玻璃表面液膜厚度,利用设计的检测系统测量电容值变化,将测量结果与COMSOL仿真结果比较并进行误差分析与数据处理,最终完成系统误差评价.实验表明：系统测量平均相对误差9.5%,分辨率达到0.1 mm,能有效分辨预应力管道内灌浆分层情况.此外,检测系统(不包括传感器)尺寸仅为100 mm×80 mm×30 mm,配有便携电源,便于在线检测.本系统能够用于预应力管道灌浆质量检测,且其检测结果准确、可靠,满足工程应用要求.

Portable System Design for Inspecting Grouting Quality of Prestressed Ducts Based on a Coplanar Capacitive Sensor

The grouting quality of post-tensioned prestressed ducts is related to the safety of bridges. An inspection system based on coplanar capacitive sensor for grouting quality was presented, which can detect the stratification of grouting in the ducts. With the derived semi-analytical equation for a double-plate capacitive proximity sensor, the optimal parameters of coplanar capacitive sensor were determined. Based on the principle of capacitive proximity sensor, data acquisition unit and data conversion unit were designed. To promote the system, system control unit and data display unit were designed. According to the approximation theory, the system verification test was designed by measuring capacitance of different thicknesses of liquid on the glass surface and comparing the measurement results with the COMSOL simulation results, error analysis and data processing were done. Finally, a system error evaluation was completed. Experiments show that the average relative error of the system is 9. 5%, the resolution is 0. 1 mm and the system can effectively distinguish stratification of grouting in the ducts. Additionally, the inspection system size ( except the sensor) is 100 mmí80 mmí30 mm and is equipped with a portable power that is convenient for online inspection. The system can be used in inspection of grouting quality of post-tensioned prestressed ducts and the test result is reliable and accurate, which can satisfy the requirements of engineering application.